Swing measurement system and method employing simultaneous multi-swing display

ABSTRACT

A system and method for measuring at least one element of motion of the swing of an athletic implement, in which electrical signals from torque, strain and flex gauges in the implement representative of successive swings are sequentially stored and then at least two signals of successive swings of one of torque, strain or flex are simultaneously displayed, as magnitude versus time, for comparison.

United States Patent n91 Evans [4 1 Feb. 19, 1974 SWING MEASUREMENTSYSTEM AND METHOD EMPLOYING SIMULTANEOUS MULTI-SWING DISPLAY Inventori-J Sines"WTEvEETJSEWTYEIEI Assignee:

Clearwater, Fla.

Filedz Ma? 56,1972

Appl. No.: 258,018

Athletic Swing Measurement Inc.,

US. Cl. 273/186 A, 340/279, 340/262, 340/282, 340/366 CA, 340/177 R,273/DIG.

Int. Cl A63b 69/36 Field of Search.. 273/186, 26, 29, 73, DIG. 28,273/183 B; 35/29 A References Cited UNITED STATES PATENTS Evans 273/183B X 10mm; sTIzAIN GAGE 3,270,564 9/1966 Evans 273/186 A X PrimaryExaminer-George J. Marlo Attorney, Agent, or FirmDuckworth, Hobby &Allen [57] ABSTRACT A system and method for measuring at least oneelement of motion of the swing of an athletic implement, in whichelectrical signals from torque, strain and flex gauges in the implementrepresentative of successive swings are sequentially stored and then atleast two signals of successive swings of one of torque, strain or flexare simultaneously displayed, as magnitude versus time, for comparison.

14 Claims, 2 Drawing Figures 22 RECEIVERS SIGNAL CONDITIONER PATENTEDFEBI 9I9T4 SIGNAL CONDITIONER A/D 12* CONVERTER 14 -ACCELEI2OMETEI2 36 38 l1 DIGITAL 2" DIGITAL N'"DIGITAL MEMORY MEMORY MEMORY y 48 52 I f 7MANUAL L50 REFERENCE- SELECTOR swING(R) STORAGE I 2 2 1 L N DISPLAYLOGIC D/A 2 DISPLAY GENERATOR CONVERTER N cONTROL I I I 56 54 -58 L 1VISUAL 2 DISPLAY SWING MEASUREMENT SYSTEM AND METHOD EMPLOYINGSIMULTANEOUS MULTI-SWING DISPLAY BACKGROUD OF THE INVENTION Thisinvention relates to measurement systems, and in particular, to systemsdesigned to measure and display the characteristics of the swing of anathletic implement.

In US. Pat. No. 3,270,564, I disclose a system for measuring threeelements of motion (velocity, torque, and flex) for the swing of anathletic implement, such as a golf club. In this system, any one or allof these three elements are sensed during the swing and converted to anelectrical signal. This signal is transmitted to a nearby console, whereit is processed and visually displayed in real-time on an oscillographor oscilloscope. In conjunction with this real-time display, the signalsrepresentative of a number of swings can be averaged, which average isthen compared with a reference swing.

In U.S. Pat. application Ser. No. 93,200, filed Nov. 27, 1970, now US.Pat. No. 3,717,857, I disclose a swing measurement system which is wornon the athletes arm.

SUMMARY OF THE INVENTION THE DRAWING FIG. '1 illustrates, partly inblock diagram form, a golf club swing measurement system which embodiesthe present invention.

FIG. 2 depicts a visual display which may be obtained from the system ofFIG. 1'.

DETAILED DESCRIPTION An embodiment of the invention is described belowwith reference to FIG. 1. In this embodiment, three elements of themotion of the swing of a golf club are measured, signals representativeof the elements for successive swings are sequentially stored, and thenthe signals for all of the swings are simultaneously displayed forcomparison. It will be understood, however, that the invention is'notlimited to this embodiment, and may be employed in a variety of otherapplications.

The embodiment of FIG. 1 includes a golf club having a club head 14 anda shaft 18. The club head 14 includes a club face 11 which is adapted tostrike a golf ball. An accelerometer 12 is located in the club head 14and is adapted to measure the velocity of the club head 14 during theswing. A torque strain gage 16 is positioned within the shaft 18proximal to the club head 14 and is adapted to measure the torque, orangular momentum, about the axis of the shaft 18 during the swing. Aflex strain gage 20 is positioned in an intermediate region of the shaft18 and is adapted to measure the flex, or bending, of the shaft 18during the swing. Each of the motion sensors (the accelerometer 12, thetorque 16, and the flex gage 20) are capable of providing an analogelectrical output which indicates the magnitude of the correspondingelement of motion (velocity, torque, and flexure, respectively) withrespect to time.

The golf club 10 further comprises means for transmitting the respectiveoutputs of the sensors l2, l6 and 20 to a nearby console for furtherprocessing and display as described below in greater detail. Thetransmission means may comprise, as shown in FIG. 1, three F.M.transmitters 22, 24 and 26 which transmit (either on three differentfrequencies or on a single multiplexed frequency) a signal modulated bythe output of the sensors 12, 16 and 20, respectively. The shaft 18 mayserve as a transmitting antenna for the transmitters 22, 24 and 26. Thesensors 12, 16 and 20 and the transmitters 22, 24 and 26 are powered bya voltage source 28, such as a DC. battery, which is located in theupper portion of the shaft 18. The golf club 10, as described thus far,is essentially identical to the instrumented golf club described in theUS. Pat. No. 3,270,564.

In an alternate arrangement of the system of FIG. 1, a carrier frequencyis transmitted from the nearby console to a passive repeater circuit inthe club 10. The carrier is modulated by the outputs of the sensors l2,l6 and 20 and transmitted to the console for processing and display.This system is disclosed in my US. application Ser. No. 205,067, filedDec. 6, I971.

The system of FIG. 1 further includes an FM receiver 30 for receivingand demodulating the transmitted signals which are representative of thevelocity, torque and flex of each swing of the club 10. The receiver 30and other signal processing and display circuits and componentsdescribed below may be housed in a record/playback console such as thatdisclosed in the aforementioned patent.

The output of the receiver 30 is fed to a signal conditioning circuit 32which includes means for amplifying the signal and discarding noise. Theoutput of the signal conditioner 32 is fed to an analog-to-digital (A/D)converter 34, where the analog outputs of the sensors l2, l6 and 20 aretranslated into a digital format.

The system of FIG. 1 also comprises aplurality of digital memorycircuits, including a first digital memory 36, a second digital memory38, and an N' digital memory 40. It will be understood that the N"digital memory 40 represents the last one of any finite number ofdigital memory circuits. The first digital memory 36 is adapted toreceive and .serially store the digital output of the analog-to-digitalconverter 34 which is representative of the three elements of motion ofeach successive swing of the golf club 10. I

The stored digital signals for each successive swing are, on call, fedout of the first memory 36 to a selector circuit 42. Input and outputcircuit means 44 and 46, respectively, are provided between the selectorcircuit 42 and-the second memory 38. Like input and output circuit meansare provided between the selector circuit 42 and each additional memory,such as the input and output circuit means 48 and 50, respectively,between the N'' digital memory 40 and the selector circuit 42. Theselector circuit 42 may comprise a manually operated switching circuitcapable of feeding the output of the first memory 36 for storage in thesecond through the N memories N" 38, 40 via the respective input means44 or 48, and then subsequently selecting and playing back the storedsignals through the respective output means 46 or 50. Alternatively, theselector circuit 42 may comprise an automatic switching arrangementwhich is designed to perform this recordplayback function into and outof the second through the N memories 38, 40. In this way, the signalsrepresentative of each successive swing can be serially stored andsimultaneously played back through the selector circuit 42.

Although it is not essential, the system may include reference swingstorage means 52 which can provide, on call, an input to the selector 42which is representative of an ideal swing of the golf club 10. Forexample, the reference swing storage means 52 may comprise a recordedtape cassette which can be plugged into the system by the operator ofthe manual selector circuit 42 nd fed into one of the auxiliary memories38, 40.

The manual selector circuit 42 has a plurality of output meand l, 2, .Nincluding one output (identified by 1 in FIG. 1) which feeds the outputof the first digital memory 36 to a digital-to-analog (D/A) converter54. Other ones of the outputs from the selector 42 feed the outputs,when played back, of the second through the N" memories 38, 40 into adisplay logic generator 56. Two of these output means are identified as2" and N" in FIG. 1, and are associated with the respective second andN" memories 38 and 40.

The display logic generator 56 generates for each output 2, .N of theselector 42, a logic which distinguishes that output from all of theother outputs of the selector. For example, output 1 may comprisesignals which will be presented as solid lines on a visual display 60.which is described below in greater detail. The logic generator 56 maythen generate digital signals for output 2 which is presented as dottedlines on the display, dashed lines for output N of the selector 42, andso on. In this way, each input to the visual display is visuallydistinguishable from the other inputs. The digital outputs 2, .N of thelogic generator 56 are then fed to the digital-to-analog converter 54.

The analog outputs l, 2, .N of the digital-toanalog converter 54 are fedto display control means 58, which may comprise, for example, thehorizontal and vertical deflection circuits of an oscillograph or anoscilloscope. The display control means 58, in turn, drives a visualdisplay 60, such as the oscillograph and oscilloscope associated withthe deflection circuitry just described.

The operation of the system of FIG. I will now be described. After thegolfer has completed one swing of the club 10, the output of the threemotion sensors 12, 16 and 20 for that swing are processed and stored inthe first memory 36. The operator of the manual selector 42 then callsup the signals representative of the one swing, which are displayed onthe visual display 60. At the same time, the operator manually selectsthe second digital memory 38, in order that the output representative ofthe one swing is stored in the second memory through selector 42.

Subsequently, the golfer completes another swing, the signalsrepresentative of which are stored in the first memory 36. The operatorof the manual selector 42 may then call up and store the signals of thisswing into a third memory, the signals of a third swing in a fourthmemory, and so on through the N" memory 40,

until signals representative of successive swings are stored in all ofthe memories. The last of the successive swings is stored in the firstmemory 36. In this way signals representative of N successive swings maybe sequentially stored-and then simultaneously displayed.

FIG. 2 illustrates three sets of simultaneous oscilloscope traces thatcan be obtained in this way. For purposes of FIG. 2, it is assumed thatthe golfer has completed the two swings described above. The signalsrepresentative of the first swing are stored in the second memory 38 andthe signals of the second swing remain stored in the first memory 36.Additionally, the operator of the manual selector 42 has called up thereference swing signals and stored those reference swing signals in theN" memory 40. After completion of the second swing and storage of thereference swing signal, the operator then calls up the stored signals inthe first through the N' memories 36, 38 and 40.

Referring now to FIG. 2, the upper trace set is of plot of the output ofthe accelerometer 12 versus time for the two swings and the referenceswing R, identified by a dashed line. The first swing is identified by adotted line, and the second swing is identified by a solid line. As seenby the reference trace R, an ideal velocity curve shows an initialreverse velocity during the back stroke, followed by a continuedincrease in velocity until impact by the club head 11 with the golfball. Impact is indicated on reference velocity curve R by the suddendrop, and sligt reversal in velocity. In the first and second swings,thee golfer has exhibited a common fault wherein impact does not occuruntil after a significant decrease in velocity. This consistent error ofthe golfer is much more apparent because of the simultaneous display ofa number of successive swings.

The middle trace set 82 of FIG. 2 isa plot of the output of the torquegage 16 versus time for the two swings and the reference swing R. Asshown by the dashed reference torque trace R, very little torque shouldoccur. However, during the first swing (dotted line), the golfer struckthe golf ball on the heel of the club head as indicated by the excessivenegative torque compartment. During the second swing (solid line), thegolfer struck the golf ball at the toe of the club head 14, as indicatedby the excessive positive torque component. Such inconsistencies arereadily apparent from the simultaneous display of several swings.

The lower trace set 84 of FIG. 2 is a plot of the output of the flexgage versus time for the two swings and the reference swing. Ideally,there is initial forward bending during the back stroke, then a negativebending (opposite to direction of swing), then there should be apositive bend, that is a bend toward the ball during the stroke up untilimpact with the ball, as illustrated by the dashed reference swing traceR. However, it has been found that frequently, the solid and dottedtraces occur, indicating a negative bending prior to impact. While inpart this may be due to a loss in velocity prior to impact, this may bedetermined by examination of velocity trace set 80 for the sameindividual. If there is no loss in velocity, a negative curve prior toimpact, as shown by the solid and dotted traces, would indicate that ahandle has been chosen which is insufficiently stiff. Alternatively, agreater club head to overall club weight should be chosen to obtain agreater momentum on the part of the club head 14. Again, these errorsare much more apparent to the golfer or an instructor by virtue of thesimultaneous display of the signals representative of a number ofsuccessive swings.

Other modifications may be employed in the system of FlG. 1. Forexample, the visual display 60 may comprise a color oscilliscope, inwhich the successive swings are each designated by different colors.Further, the storage means can comprise an analog memory arrangementsuch as that described in the US. Pat. No. 3,270,564.

l claim:

1. A measurement system comprising:

an athletic implement;

motion sensing means responsive to successive movements of saieimplement for providing a sequence of electrical signals, each of whichis a function of at least one element of motion of a correspondingmovement;

means responsive to a plurality of input signals for providing asimultaneous visual display representative of said input signals; and

signal processing means responsive to sequential outputs of said motionsensing means for simultaneously providing said input signals to saiddisplay means.

2. A measurement system as recited in claim 1, wherein said motionsensing means comprises a sensor responsive to one of velocity, torque,and flex during movement of said implement.

3. A measurement system as recited in claim 2, wherein said signalprocessing means comprises means for sequentially storing said motionelement signals.

4. A measurement system as recited in claim 3, wherein said sequentialstoring means comprises at least two memory means, one of said memorymeans being adapted to receive an output from another one of said memorymeans.

5. A measurement system as recited in claim 4, further comprising meansfor selecting an output from said another memory means for storing insaid one memory means.

6. A measurement system as recited in claim 5, wherein said selectingmeans further comprises means for playing back said output stored insaid memory means simultaneously with another output of said anothermemory means.

7. A measurement system as recited in claim 6, further comprising meansresponsive to the simultaneous outputs of said selecting means forproviding inputs to said visual display means each of which is visuallydistinguishable from all other inputs.

8. An athletic swing measurement system, comprising:

an athletic implement adapted for swinging to strike an object; motionsensing means responsive to successive swings of said implement forproviding a sequence of electrical signals which are representative ofat least one element of motion of successive swings;

signal processing means responsive to said sequence of signals forproviding outputseach of which represents said element of motion foreach successive swing;

first and second memory means, said first memory means responsive tosaid processing means for serially storing each successive one of saidoutputs; selector means for feeding one output of said first memorymeans into said second memory means,

said selector means further comprising means for playing back said oneoutput out of said second memory means simultaneously with anotheroutput of said first memory means; and

5 visual display means responsive to said one and another outputs fromsaid selector means for providing a simultaneous visual displayrepresenting said outputs. 9. An athletic swing measurement system asrecited 10 in claim 8, further comprising:

an additional number of said memory means; and

wherein said selector means comprises means for feeding and playing backanother, and subsequent outputs of said first memory means serially intoand out of said additional memory means.

10. An athletic swing measurement system as recited in claim 9, furthercomprising means for providing a reference swing input to said selectormeans.

11. An athletic swing measurement system as recited in claim 9, furthercomprising logic generating means electrically interposed between saidselector means and said visual display means, said logic generatingmeans responsive to outputs of said second and additional memory meansfor providing inputs to said visual display each of which is visuallydistinguishable from other inputs thereto.

12. A gold club swing measurement system, comprising:

a golf club having a shaft with a club head attached thereto;

motion sensing means carried by said golf club and responsive to aplurality of successive swings of said club for providing an electricsignal which is a function of at least one element of motion'of eachswing;

means supported by said shaft for transmitting an output modulated byeach said signal;

means for receiving and demodulating said output of said transmittingmeans and reproducing each said signal;

means responsive to an output of said receiving means for convertingeach said signal to a series of digital values;

- first and second memory means, said first memory means providing meansfor serially storing the digital values representative of eachsuccessive swing;

selection means responsive to an output of said first memory means forrecording and playing back the digital values representative of oneswing into and out of said second memory means; and

means responsive to outputs of said selection means for simultaneouslyproviding visual displays representative of said element of said oneswing and a like element of another, successive swing.

13. A system as recited in claim 12, further comprising logic generatingmeans responsive to the output of said selection means representative ofsaid one swing for generating a logic which distinguishes said visualdisplay of said one swing from that of said another swing.

14. A method for measuring and displaying an element of motion of oneswing of an athletic implement and a like element of a subsequent swing,comprising the steps of:

sensing said motion element for said one swing;

age; rendering one of said signals distinguishable from the othersignal; and simultaneously providing a visual display representative ofsaid signals.

1. A measurement system comprising: an athletic implement; motionsensing means responsive to successive movements of said implement forproviding a sequence of electrical signals, each of which is a functionof at least one element of motion of a corresponding movement; meansresponsive to a plurality of input signals for providing a simultaneousvisual display representative of said input signals; and signalprocessing means responsive to sequential outputs of said motion sensingmeans for simultaneously providing said input signals to said displaymeans.
 2. A measurement system as recited in claim 1, wherein saidmotion sensing means comprises a sensor responsive to one of velocity,torque, and flex during movement of said implement.
 3. A measurementsystem as recited in claim 2, wherein said signal processing meanscomprises means for sequentially storing said motion element signals. 4.A measurement system as recited in claim 3, wherein said sequentialstoring means comprises at least two memory means, one of said memorymeans being adapted to receive an output from another one of said memorymeans.
 5. A measurement system as recited in claim 4, further comprisingmeans for selecting an output from said another memory means for storagein said one memory means.
 6. A measurement system as recited in claim 5,wherein said selecting means further comprises means for playing backsaid output stored in said one memory means simultaneously with anotheroutput of said another memory means.
 7. A measurement system as recitedin claim 6, further comprising means responsive to the simultaneousoutputs of said selecting means for providing inputs to said visualdisplay means each of which is visually distinguishable from all otherinputs.
 8. An athletic swing measurement system, comprising: an athleticimplement adapted for swinging to strike an object; motion sensing meansresponsive to successive swings of said implement for providing asequence of electrical signals which are representative of at least oneelement of motion of successive swings; signal processing meansresponsive to said sequence of signals for providing outputs each ofwhich represents said element of motion for each successive swing; firstand second memory means, said first memory means responsive to saidprocessing means for serially storing each successive one of saidoutputs; selector means for feeding one output of said first memorymeans into said second memory means, said selector means furthercomprising means for playing back said one output out of said secondmemory means simultaneously with another output of said first memorymeans; and visual display means responsive to said one and anotheroutputs from said selector means for providing a simultaneous visualdisplay representing said outputs.
 9. An athletic swing measurementsystem as recited in claim 8, further comprising: an additional numberof said memory means; and wherein said selector means comprises meansfor feeding and playing back another, and subsequent outputs of saidfirst memory means serially into and out of said additional memorymeans.
 10. An athletic swing measurement system as recited in claim 9,further comprising means for providing a reference swing input to saidselector means.
 11. An athletic swing measurement system as recited inclaim 9, further comprising logic generating means electricallyinterposed between said selector means and said visual display means,said logic generating means responsive to outputs of said second andadditional memory means for providing inputs to said visual display eachof which is visually distinguishable from other inputs thereto.
 12. Agolf club swing measurement system, comprising: a golf club having ashaft with a club head attached thereto; motion sensing means carried bysaid golf club and responsive to a plurality of successive swings ofsaid club for providing an electrical signal which is a function of atleast one element of motion of each swing; means supported by said shaftfor transmitting an output modulated by each said signal; means forreceiving and demodulating said output of said transmitting means andreproducing each said signal; means responsive to an output of saidreceiving means for converting each said signal to a series of digitalvalues; first and second memory means, said first memory means providingmeans for serially storing the digital values representative of eachsuccessive swing; selection means responsive to an output of said firstmemory means for recording and playing back the digital valuesrepresentative of one swing into and out of said second memory means;and means responsive to outputs of said selection means forsimultaneously provIding visual displays representative of said elementof said one swing and a like element of another, successive swing.
 13. Asystem as recited in claim 12, further comprising logic generating meansresponsive to the output of said selection means representative of saidone swing for generating a logic which distinguishes said visual displayof said one swing from that of said another swing.
 14. A method formeasuring and displaying an element of motion of one swing of anathletic implement and a like element of a subsequent swing, comprisingthe steps of: sensing said motion element for said one swing; storing anelectrical signal representative of said motion element for said oneswing; sensing said motion element for said subsequent swing; storing anelectrical signal representative of said motion element for saidsubsequent swing; simultaneously playing back said signals from storage;rendering one of said signals distinguishable from the other signal; andsimultaneously providing a visual display representative of saidsignals.